Impact of controlled shearing on solubility and heat stability of pea protein isolate dispersed in solutions with adjusted ionic strength

Pea protein isolates (PPI) have sustained an increasing demand in the food industry as a substitute for animal-origin proteins. Shearing is an integral part of food processing that can change properties of proteins and their functionality. PPI dispersions prepared at 4 or 8% concentration (w/w protein), pH 6.8 or 7.5 and under ionic strength (IS) 100, 200 mM or non-adjusted, were subjected to controlled shearing at two levels (100 or 1500 s(-1)) during heating at 90 degrees C for 5 min. All main factors had substantial effects on the tested dependent variables. Shearing at 1500 s(-1) significantly improved the solubility and heat stability of 4% PPI at pH 6.8 or 7.5 and IS 100 or 200 mM by 27-43% in comparison to 100 s(-1). Following 1500 s(-1) treatment, all PPI dispersions showed > 85% solubility and heat stability except 4% PPI at pH 6.8 and IS 100 mM (60%). Shearing appeared to alter structural and physicochemical properties of pea proteins as well nature of protein aggregation. Heating accompanied with 100 s(-1) shearing mostly resulted in insoluble covalent aggregates while shearing at 1500 s(-1) mainly contributed to formation of soluble hydrophobic aggregates.